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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Low velocity impact testing
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<blockquote data-quote="RockyMtnMT" data-source="post: 1181776" data-attributes="member: 7999"><p>We have been working with low velocity impact testing the last few weeks to make sure that our bullets do as they should. There have been some great threads on this in the years past. Discussions about twist rate of reduced loads and the effect that it has on the impact test. We have been working on finding minimum impact velocity for our bullets to open up. We were working with the .243 80g bullet. When fired from a 9" twist with a muzzle vel of 1800fps they would not open up. We then fired it from a 7" twist at the same vel and they opened perfectly. So my conclusion is that the faster twist gave better stability to keep the bullet oriented point 1st and ensuring expansion. This 80 bullet at 1800fps has a stability factor of 1.41 sg at our altitude in the 9" twist. Slightly low. In the 7" twist it is 2.33 sg, very stable.</p><p></p><p>So my conclusion is that stability factor may have more to do with terminal ballistics than previously thought. A bullet that is marginally stable will fly very well and will lose a but of bc. I now also think that that bullet that is a little marginal in stability may not work like it should when impacting an animal.</p><p></p><p>Steve</p></blockquote><p></p>
[QUOTE="RockyMtnMT, post: 1181776, member: 7999"] We have been working with low velocity impact testing the last few weeks to make sure that our bullets do as they should. There have been some great threads on this in the years past. Discussions about twist rate of reduced loads and the effect that it has on the impact test. We have been working on finding minimum impact velocity for our bullets to open up. We were working with the .243 80g bullet. When fired from a 9" twist with a muzzle vel of 1800fps they would not open up. We then fired it from a 7" twist at the same vel and they opened perfectly. So my conclusion is that the faster twist gave better stability to keep the bullet oriented point 1st and ensuring expansion. This 80 bullet at 1800fps has a stability factor of 1.41 sg at our altitude in the 9" twist. Slightly low. In the 7" twist it is 2.33 sg, very stable. So my conclusion is that stability factor may have more to do with terminal ballistics than previously thought. A bullet that is marginally stable will fly very well and will lose a but of bc. I now also think that that bullet that is a little marginal in stability may not work like it should when impacting an animal. Steve [/QUOTE]
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Low velocity impact testing
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